Fix incorrect users routes.
Add basic user signup specs and get to green.

Add strong parameters to users controller. Implement initial new and create actions.
Switch to using 'users' resource for routing.
Update formatting for user model spec.

Add a describe block that wraps all of the "User attributes" specs.
Create sessions controller and initial signin page and specs.

Implementation current doesn't include any signin functionality, only signin page and page specs.
Add sessions resource to routes file and add 'signup', 'signing', and 'signout' matches. Also, point root to signup page.
Add header partial with unstyled signin/signout links.
Include SessionsHelper in ApplicationController
Add call to 'sign_out' on handle_unverified_request
Add auth_token attribute to users table.

Includes corresponding (light) addition to User model spec.
Implement user auth_token creation (before create).

Commit includes a light spec that checks to make sure auth_token is being set upon user creation.
Add callback to User model that downcases all email attributes before saving them to the DB.
Delete handle_unverified_request modification.
Use form_tag for sessions#new view.
Fix header helper link typo.
Show current user on users#show view (for debugging).
Implement user sessions.
Add before actions for correct user and signed in user in Users controller.
Add small cosmetic changes to views (for testing).
Add small syntax updates to two authentication pages specs.